214 POOLE ON THE GREA.T AMERICAN DESERT. 



certain districts of the region reveals indications, not very distinct, 

 but suggestive of doubt whether the ancient sea did not extend to 

 even a greater altitude, than where the well-marked terraces define 

 its sometime boundary : a doubt which further attention to the 

 subject almost changes into a belief. The old overland road after 

 leaving the desert, and before entering the confines of Nevada, 

 crosses the Deep Creek, which flows through a narrow elevated 

 valley, on the sides of which at an elevation of 1800 feet above the 

 lake, great beds of gravel uniformly deposited, and evidently by 

 water, have the same parellelism which is so discernible in the 

 valleys opening into the Desert and Great Salt Lake. The lines 

 of level which elsewhere cannot fail to catch the eye, are here 

 through time almost obliterated, and can only be detected when 

 viewing an extended range of country. 



What has been the origfin of these ojravel beds ? For beds of a 

 similar character are also to be met with in many other elevated 

 valleys. They are evidently not fluviatile. Are they lacustrine ; 

 or can they possibly be marine ? Lying as they do truly horizon- 

 tal, it is highly improbable that they can be marine, and were 

 formed when the mountain ranges as islands were emerging from 

 the ocean. Were this possibly the case, then the whole of that 

 country lying between the Wahsatch and the Sierra Nevada must 

 have been bodily elevated 6,000 feet without tilting or breaking in 

 any degree the uniformity of these superficial deposits. And yet 

 if the valleys of this elevated region were not filled by the action of 

 marine denudation, we are forced to conclude, improbable as it 

 may at first seem, that they were by subaerial agency, and that 

 the agent which formed the benches was a lake of fresh water.* 

 A lake which must have extended over the major part of the greater 

 interior basin, and have had its surface at one time, nearly, if not 

 quite, 2,000 feet above the present level of the Salt Lake. It is 



* In digging a well near Salt Lake City, fresh water shells were found some 

 forty feet below the surface in the gravel deposits, and on the north side of the 

 lake, the cuts on the railroad, through the gravel and sand, reveal the greatest 

 abundance of fresh water shells. The species that seem to have been most abun- 

 dant is Fluminicola fusca. Varieties of Limnea^ Valvaia and Amnicola, were also 

 discovered. — Hatden. 



